Injection device comprising an improved delivery element

ABSTRACT

An injection device having a delivery element with an inner thread may be driven by rotation and includes a cylindrical outer wall region, which is substantially smooth. Such features provide a delivery element configured such that it is less intimidating to patients than known threaded rods, and may facilitate easy cleaning. The delivery element may be non-rotatably guided and axially spring-loaded, and may be inserted axially into the housing when the reservoir is replaced. The driving thread element for the delivery element may be mounted in the vicinity of the distal end of the housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/455,243 filed Aug. 8, 2014, which is a continuation of U.S. patentapplication Ser. No. 12/403,775 filed Mar. 13, 2009, issued as U.S. Pat.No. 8,834,431 on Sep. 16, 2014, which is a continuation of InternationalPatent Application No. PCT/CH2007/000241 filed May 11, 2007, whichclaims priority to Swiss Patent Application No. 1475/06 filed Sep. 15,2006, the entire contents of both of which are incorporated herein byreference.

BACKGROUND

The present invention relates to devices for administering, injecting,delivering, infusing or dispensing a substance, and to methods of makingand using such devices. More particularly, it relates to such a devicefor delivering a fluid product, wherein the device can be developed asan injection device for the injection of an adjustable dose of theproduct and can take the form of an injection pen, i.e. a compactinjection device in pen-like form.

A large number of injection devices are known from the prior art for thedosed administering of medicaments or therapeutic agents such asinsulin, growth hormones or osteoporosis drugs, which must beadministered regularly. Such devices are on the one hand intended toreliably and precisely deliver a dose which is able to be pre-set. Onthe other hand, they are intended to be user-friendly to a high degree.This applies all the more because they are generally operated by aperson for self-administration.

The medicament can be housed in an exchangeable carpule (which also maybe thought of and/or referred to as an ampoule, receptacle, container orreservoir), which is able to be inserted into a carpule holder. Thelatter can then be associated with or fastened to a housing of theinjection device, e.g. by a screw connection or a bayonet connection.For distribution, a product stopper or piston in the carpule is pushedforward (toward the needle associated with the injection device) by adelivery arrangement with a delivery element in the form of a pistonrod.

Compact, pen-shaped administering devices are known, in which thedistribution takes place automatically after a first triggering (e.g.“power-assisted pens”). The dose in such devices is generally pre-set bya rotation of a dosing button. A drive is present in the device, e.g. aspring drive, which is tensioned on setting of the dose. The device istriggered by pressing a triggering arrangement, which can be identicalto the dosing button. In so doing, the drive generates a drive movement,e.g. in the form of a rotary movement, which is converted into anadvancing movement of the piston rod. In the case of a drive by a rotarymovement, the piston rod may be constructed as a threaded rod on which adrive nut runs. Examples of such injection pens are disclosed in DE-A 102004 063 644, DE-A 10 2004 063 647, WO-A 2004/002556 and DE-A 102 29122.

In EP-A 1 681 070, a manually driven injection pen is disclosed, whereinthe piston rod is hollow and has an internal thread instead of anexternal thread. This internal thread is in engagement with the externalthread of a rotatable drive shaft, which, in the region of its proximalend, is mounted opposite an inner housing part. The piston rod has onits outer side continuous longitudinal grooves into which projections ofa fixing bush engage. This fixing bush is secured relative to thehousing when a receptacle holder is connected with the housing, and canfreely rotate when the receptacle holder is detached from the housing.On administering of a dose, the drive shaft rotates and thereby advancesthe piston rod linearly, which is guided to be locked against relativerotation via the fixing bush. In the case of a change of reservoir, thereceptacle holder is detached from the housing. Thereby, the fixingbush, and with it also the piston rod, is freely rotatable with respectto the housing. When the piston rod is pushed into the housing, thedrive shaft remains stationary and the piston rod performs a screwmotion.

This device is capable of improvement in several respects. For example,the screw motion of the piston rod compulsorily requires, on insertion,that at its distal end a cap is rotatably mounted, which, on insertion,does not co-rotate with the piston rod, because otherwise on insertionno suitable counter-surface would be available which is locked againstrelative rotation, on which the axial force, required for insertion,could engage. Furthermore, the presence of the fixing bush requires thatlongitudinal grooves are formed on the outer side of the piston rod.Dirt can accumulate in these. Moreover, a bearing of the drive shaftrelative to the housing in its proximal end region is disadvantageous,because a large amount of space is required for this in a region inwhich otherwise, for example, drive components could be housed. Also, inthis device it is not ensured that the piston rod also actually touchesthe stopper of the medicament reservoir.

SUMMARY

In accordance with the present invention, and according to a firstaspect of the presently disclosed embodiments, a device foradministering a fluid product includes a housing and a delivery elementfor the delivery of the product from a reservoir. The delivery elementis movable relative to the housing along a thrust axis. Instead of anexternal thread, the delivery element has an internal thread, the threadaxis of which runs along the thrust axis. Thereby, the thread is usedfor the drive is not visible to the user, and the outer side of thedelivery element may thus have a variety of configurations, and forexample, may be adapted to the needs of the user and other technicalrequirements. In addition, a compact arrangement becomes possible. Thedevice comprises a drive arrangement and a thread element with anexternal thread, which is in engagement with the internal thread of thedelivery element, and may be fixed relative the housing along the thrustaxis and may be set in a rotary movement about the thrust axis by thedrive arrangement to advance the delivery element along the thrust axis.

According to certain embodiments, the delivery element is guided so asto be locked against relative rotation with respect to the housing in anumber of instances, and therefore performs a linear thrust movementboth on the thrust movement for the ejection of the product and also onpushing back on the change of a receptacle.

In some embodiments, the thread element may be constructed as anexternal threaded rod, and the delivery element may include a shortinternal thread, compared with the external thread of the threadelement, only in the region of its proximal end, to minimize frictionlosses.

In some embodiments, the delivery element may be spring-loaded in adistal (forward) direction, i.e., the direction in which the thrusttakes place. The spring cooperating with the delivery element may beconfigured and arranged so as to not bring about an ejection of theproduct out of the reservoir. Rather, it serves, in the case of areservoir change, to bring the delivery element automatically into itsdistal final position, i.e., to move it out completely, when thereservoir is removed from the housing. In this way, the delivery elementmay touch the reservoir stopper at all times. The corresponding springmay be housed in the interior of the thread element configured as ahollow spindle, may be configured as a helical spring, and may be guidedon a guide needle.

In certain embodiments, the device includes a receptacle holderdetachable from the housing to hold the reservoir with the product. In astate in which the receptacle holder is detached from the housing, thethread element may be rotatable with respect to the housing such thatthe delivery element is insertedable into the housing by an axialdisplacement in the proximal direction. Here, the thread elementco-rotates forming a the threaded engagement with the delivery element.

In some embodiments, the delivery element is surrounded radially atleast partially by a guide sleeve with a proximal and a distal end. Thelength of this guide sleeve may correspond at least to the maximumthrust range of the delivery element, i.e., the distance between thedistal and the proximal (rearward) final position of the deliveryelement. Close to its distal end, the guide sleeve is connected, atleast during the administering, so as to be locked against relativerotation with the housing or with an element fixed to the housing. Thedelivery element is guided along the thrust direction so as to be lockedagainst relative rotation in the guide sleeve. For this, the deliveryelement, at least in the region of its proximal end, may be in anengagement, locked against relative rotation, with the interior of theguide sleeve, which engagement, however, permits an axial displacement.For this, in the region of the proximal (rear) end, an engagementstructure, e.g., in the form of several longitudinal ribs, may beconfigured to project radially outward from the outer peripheral surfaceof the delivery element, cooperating with a complementary structure,e.g., in the form of several longitudinal grooves on the innerperipheral surface of the guide sleeve. The device may comprise, inaddition, an outer sleeve with a proximal and a distal end, which,radially surrounds the guide sleeve at least partially. Close to itsproximal end, this outer sleeve is connected with the rotatable element.Close to its distal end, the outer sleeve is rotatable and is guided soas to be secured with regard to displacement relative to the guidesleeve.

Accordingly, in the exemplary embodiments provided herein, the deliveryelement may be secured against rotation relative to the stationaryhousing and guided longitudinally. In some embodiments, the deliveryelement may be configured, on its outer side, with a substantiallysmooth surface. Thus the delivery element is guided longitudinally inthe region of its proximal end in an element, which is locked againstrelative rotation with respect to the housing. However, such aconfiguration may require that the delivery element, which is lockedagainst relative rotation, have a length such that the guiding isprovided over the range of the thrust of the delivery element.Accordingly, a sleeve-like structure of the element, which is lockedagainst relative rotation, is provided, which is therefore designated asa guide sleeve, with a length of this guide sleeve corresponding atleast to the thrust range of the delivery element. To drive the deliveryelement, the rotatable element may be arranged inside the deliveryelement. To provide a thread or threaded engagement over the thrustrange, the rotatable element may extend at least over a length ofproximal to distal into the delivery element which corresponds to thethrust range. Access to the rotatable element, and in some embodiments,the one available access, may be provided here from the proximal end. Adriving of the rotatable element may therefore take place over itsproximal end. At the same time, the rotatable element may be mounted inany manner relative to an element which is fixed to the housing. Thismounting absorbs axial forces, which are transmitted from the deliveryelement via the thread engagement to the rotatable element. A mountingmay be provided directly at the proximal end of the rotatable element.However, this would take up a large amount of space in a region, whichis to be available for other functions.

It therefore may be desirable to reposition the site of the bearing toanother location, e.g., as close as possible to one of the ends of thehousing. This may take place by using the outer sleeve, which issecurely connected with the rotatable element and continues along theouter side of the guide sleeve towards the distal direction. Mounting isprovided between the outer sleeve and the guide sleeve, and namely inthe region of the distal (forward) end of the outer sleeve. As a result,a compact unit may be provided, the mounting of which, taking up arelatively large amount of space radially, comes to lie in a proximal(rear) region, thus enabling the injection device to accommodate furtherelements in the radial intermediate space between the outer sleeve andthe housing. Furthermore, because the outer sleeve (and thus therotatable element) is mounted on the guide sleeve and not, for instance,on the housing itself, the guide sleeve, outer sleeve, mounting,rotatable element and delivery element may be formed as a unit, and maybe movable systematically with respect to the housing, e.g., in thechangeover of a receptacle.

According to further embodiments, an injection device for theadministering of a fluid product in accordance with the presentinvention comprises a housing and a delivery element for the delivery ofthe product from a reservoir. The delivery element is movable relativeto the housing along a thrust axis between a proximal (rearward) initialposition and a distal (forward) final position, and may be guided so asto be locked against relative rotation. The delivery element may projectthrough a passage opening in a boundary wall of the housing. A drivearrangement may be configured for producing a rotary movement of arotatable element relative to the housing, wherein the rotatable elementis coupled with the delivery element so that the rotary movement bringsabout a thrust movement of the delivery element along the thrust axis.The delivery element may have a substantially smooth outer wall region,the length of which corresponds at least to the distance between thedistal final position and the proximal initial position. In this way, itbecomes possible to arrange the delivery element so that during thethrust, the smooth outer wall region is advanced through the opening inthe housing wall. Thus, viewing an external thread, which could have adeterrent effect on the user may be avoided. Also, the need to clean athread or threading is avoided or at least minimized.

A “substantially smooth” outer wall region is a region of the outerperipheral surface of the delivery element, that does not have anytechnically necessary structures (except as otherwise indicated), e.g.,no structures such as threads, deep relieved regions, highly raisedregions or grooves are present, which could lead to an insufficientacceptance by the user or could make cleaning difficult. On the otherhand, however, the outer wall region may be configured, for example,with fine structures like micro- or nano-structuring. Distally from thesmooth outer wall region, for example, a structure may adjoin, which isconfigured to advance a stopper in the product container, e.g., a thrustflange projecting radially over the outer wall region. The regionarranged proximally from the outer wall region, on the other hand, isnormally situated permanently inside the housing and is thereforeinvisible to the user. This proximal region may therefore be providedwith a configuration as desired or that meets technical requirements.

If the thrust of the delivery element is to take place via an externalthread on which a drive nut runs in a conventional manner, then thisexternal thread may adjoin the smooth outer wall region proximally.

In some embodiments, the delivery element is sealed so as to befluid-tight, at least protected against splash water, with respect tothe housing or to an element fixed to the housing. Thereby, apenetration of fluids may be prevented.

A corresponding seal may be constructed directly between the deliveryelement and the housing. However, a first seal may be constructedbetween the delivery element and an element that is movable relative tothe housing, and a second seal is constructed between the movableelement and the housing. The movable element may be arranged, forexample, so that it is movable when the reservoir is being changed, andis immovable with respect to the housing during the actualadministering. It may be cylindrical or sleeve-shaped.

In some embodiments, a substantially smooth, cylindrical, e.g., circularcylindrical, outer wall region is surrounded by at least one ring-shapedsealing element. In this way, a sealing may be achieved, as is notpossible in the case of other known piston rods with external threading,which would oppose or interfere with an efficient sealing effect. Aspresently proposed, the length of the substantially smooth outer wallregion, e.g., without structures such as threads or grooves, correspondsat least to the distance between the distal final position and theproximal initial position, between which the delivery element ismoveable in the course of the administering, to provide a sealing overthis entire region. The outer wall region may have fine structures, e.g.scales, a pattern or texture, in the range below 100 micrometers, e.g.,below 10 micrometers, which are suited to at least not impair thesealing effect, or may improve it, e.g., a micro- or nano-structuring.These structures may have a selected direction to inhibit a flow offluids.

In some embodiments, the at least one ring-shaped sealing elementcomprises at least one circumferential, flexible sealing lip, whichrests on the cylindrical outer wall region and acts in the manner of awindscreen wiper as a stripper. The contact angle between the sealinglip and the outer wall region may be to less than 90 degrees. However,it can also be constructed for example as a ring with a round orpolygonal cross-section.

In some embodiments, the interior of the housing may be sealed in afluid-tight manner with respect to the exterior of the housing, i.e.,not only in the region in which the delivery element is guided outwards,but also in other regions, e.g., in the region of movable dosing oractuating elements.

In some embodiments, the delivery element or an element cooperatingtherewith in a sealing manner may be composed of a hydrophobic materialor may be coated hydrophobically, in order to achieve or improve asealing effect, thus avoiding a creeping due to a capillary effect.

In some embodiments, the reservoir may be held in a receptacle holder,and may be fastened to the housing in a detachable manner. On fastening,this receptacle holder is guided with respect to the housing such that,relative to the housing, it carries out a combined rotary movement abouta rotation axis and a translation movement along the rotation axis. Thedevice may further comprise a spring element and a detent element. Theseelements may be arranged such that the spring element produces a springforce onto the detent element acting substantially along the rotationaxis. The detent element thereby brings about in a predetermined holdingposition of the receptacle holder, a detachable detent connection, bywhich the receptacle holder is fixed relative to the housing. Forexample, a projection of the detent element can project into adepression of the receptacle holder or of an element, which is lockedagainst relative rotation with respect thereto. A reverse arrangement isalso conceivable. The detent connection may be configured so that it isable to be detached through a movement of the receptacle holder relativeto the housing, which is opposed to the movement on fastening, i.e., thedetent connection does not need to be unlocked manually.

Therefore, a connection in the manner of a screw or bayonet connectionis provided between the receptacle holder and the housing or betweenelements connected with these. In conventional bayonet connectionsbetween two elements, an element with a bayonet pin is guided in asuitably formed slit or in a corresponding groove in the manner of aconnecting link guide of the other element, until the bayonet pinreaches a final position (corresponding to the holding position). Insuch connections, an unintentional sliding back of the pin out of thefinal position may be a problem. A similar problem also occurs in screwconnections, which are fixed by a clamping force and which may similarlybecome detached unintentionally. The device presented herein addressesthis problem by providing, in some preferred embodiments, an axiallyspring-loaded (and axially movable) detent element. Such a detentelement provides a defined fixing of the receptacle holder in theholding position, without the risk of an unintentional detachment. Theconnection may be detachable again by overcoming a sufficiently greatforce. Here, an abrasion, which could lead to a wearing out of theconnection, is avoided. By the detent element being spring-loaded intothe axial direction, the detent element and the spring element providefor space-savings.

The receptacle may be a container with a cylindrical wall region andwith a stopper displaceable therein, e.g., a carpule, which defines alongitudinal direction and is housed in a receptacle holder with acorrespondingly elongated form. When fastening on the housing, thereceptacle holder may be rotated about this longitudinal direction,i.e., the rotation axis coincides with the longitudinal axis. For theadministering of the product, the stopper is advanced by the deliveryelement along the longitudinal direction. That is, the thrust directionof the delivery element corresponds to a direction along the rotationaxis about which the receptacle holder is rotated during its fastening.

The arrangement of the spring and detent element may be provided with avariety of configurations. According to a certain embodiments, thedetent element is locked against relative rotation with respect to thehousing, and in the detent position, it is detachably engaged with anelement which is locked against relative rotation with respect to thereceptacle holder. In other words, the detent element does not followthe rotation of the receptacle holder, but remains locked againstrelative rotation with respect to the housing on fastening of thereceptacle holder. However, the reverse arrangement is also conceivable,in which the detent element is locked against relative rotation withrespect to the receptacle holder.

In various embodiments, the device comprises a carrier element, which isrotatably arranged relative to the housing. The carrier element isguided with respect to the housing such that, on fastening of thereceptacle holder on the housing and on detaching the receptacle holderfrom the housing, it is entrained by the receptacle holder and is setinto a movement, which comprises a rotary movement about the rotationaxis. In the holding position of the receptacle holder, the detentelement brings about a detachable detent connection, by which thecarrier element is fixed relative to the housing. This, in turn, holdsthe receptacle holder. The receptacle holder is therefore fixedindirectly, via the carrier element, relative to the housing. Thereby, agreater freedom is made possible in the design of the receptacle holderand of the detent element and spring element.

In some embodiments of the present invention, an injection device alsocomprises a guide element arranged so as to be locked against relativerotation with respect to the housing, which guide element can beconstructed as a guide sleeve. This guide element can be rigidlyconnected with the housing, can be configured integrally therewith, orit can be displaceable axially with respect to the housing. The carrierelement, which can likewise be formed as a sleeve, and can then bedesignated as a bayonet sleeve, is connected at least rotatably with theguide element. The spring element and the detent element may be arrangedso as to be locked against relative rotation with respect to the guideelement, and in the holding position of the receptacle holder, thedetent element is engaged detachably with the carrier element. Forexample, the guide element may be connected so as to be axiallydisplaceable with respect to the housing and the carrier element may beconnected rotatably, but axially secure as regards displacement, withthe guide element. Through this configuration, additional parts of thedevice, arranged in the housing, which are connected with the guideelement, are displaced axially when the receptacle holder is mounted onthe housing. Thereby, the administering device may be automaticallyreset for example on detaching of the receptacle holder, and onfastening of the receptacle holder, it can be brought into a state readyfor operation again. Upon detaching of the receptacle holder, theinterior of the device (e.g., the drive arrangement and, if applicable,a triggering arrangement connected therewith) may be moved in a distaldirection so that the triggering arrangement, which can be formed as apush button, is drawn into the housing and thus indicates that thedevice is not ready for operation.

In some embodiments, the carrier element may be guided with respect tothe housing such that on fastening of the receptacle holder to thehousing, it is entrained by the receptacle holder and is set into acombined rotational movement relative the housing about the rotationaxis and translation movement along the rotation axis in a proximaldirection.

In some embodiments, the carrier element may be moveable between twodefined final positions, and the detent element brings about in bothpositions a detachable detent connection, by which the carrier elementis fixed relative to the housing. The carrier element assumes its firstfinal position when the receptacle holder assumes its holding position,and assumes its second final position when the receptacle holder isremoved from the housing. The detent element may be detachably engagedboth in the first final position and also in the second final positiondirectly with the carrier element.

In some embodiments, the carrier element may be guided in at least oneguide slit relative to the housing, i.e., on the housing itself or on anelement which is fixed to the housing by one or more corresponding pins.Upon fastening to the housing, the receptacle holder may be guided in atleast one guide slit, in the manner of a bayonet connection, relative tothe housing.

In some embodiments, the detent element may be constructed in the formof a ring which extends around the rotation axis and/or around thethrust element. Suitable detent noses can be constructed on the ring.The detent element may be axially spring-loaded by a separate springelement. This may be, for example, a helical spring subjected topressure, or another type of elastic element. However, the springelement may be configured as a ring extending around the rotation axisand may be curved about an axis perpendicularly to the rotation axis, sothat the spring force is produced by a compressing of the spring elementalong the rotation axis.

In some embodiments, the detent element may be constructed integrallywith the spring element, and the detent element can be constructed as aprojection, protruding in the direction of the rotation axis, on thespring element. The detent element may be provided in this manner whenthe spring element has a curved ring configuration.

In some embodiments, the device may further comprise at least one ballbearing, which absorbs forces which are transmitted between the deliveryelement and the housing. By a ball bearing being provided, frictionallosses caused during the administering, due to the transmission offorces between the delivery element and the housing, are largelyminimized. A ball bearing may be provided when the device comprises atleast one rotatable element cooperating with the delivery element, and adrive arrangement for generating a rotary movement of the rotatableelement relative to the housing, with the rotary movement of therotatable element bringing about a thrust movement, e.g., linear thrustmovement, of the delivery element along the thrust axis in a distaldirection, by a thread engagement, e.g., a non-locking threadedengagement. In this case, the ball bearing may be arranged such that itabsorbs (axial) forces acting along the thrust axis, which aretransmitted from the delivery element, and which may be locked withrespect to rotation relative to the housing, via the rotatable elementto the housing, i.e., which act between the rotatable element and thehousing. That is, axial forces acting in a proximal direction may betransmitted between the delivery element and the housing via a rotatableconnection, which is secure with respect to displacement in the axialdirection. In known devices, a sliding connection is generally providedbetween the rotatable element and the housing or an element which isfixed to the housing. In some of the exemplary embodiments describedherein, on the other hand, at least one ball bearing is provided, whichmay be arranged between the rotatable element or an element connectedtherewith on the one hand, and the housing or an element which is fixedto the housing at least during the administering, on the other hand.Thereby, frictional losses during the rotation of the rotatable elementcan be avoided.

In further embodiments, two ball bearings are provided, and may bearranged so that they can absorb forces along the thrust axis both in aproximal direction and also in the distal direction opposite thereto,i.e., the direction in which the thrust takes place. Axial forces in theproximal direction occur during the administering, whereas axial forcesin the distal direction may occur when the delivery element isspring-loaded in the distal direction. The spring serving for this maybe arranged and configured with a relatively weak resistance such thatit does not cause any ejection of the product out of the reservoir.Rather, it serves, in a change of reservoir, to automatically bring thedelivery element into its distal final position, i.e., to move itoutward, when the reservoir is removed from the housing. When thedelivery element is in a suitable connection with the rotatable element,this leads to the rotatable element being set into a rotation when thedelivery element moves out due to the spring force. To keep the springforce low, a ball bearing may facilitate this because with the movingout of the delivery element, the ball bearing minimizes frictionalforces.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective exploded view of an exemplary embodiment of aninjection device according to the present invention;

FIG. 1B is a detail view of a surface structure provided on the thrustsleeve;

FIG. 2 is a longitudinal section through the injection device of FIG.1A;

FIG. 3 is an enlarged cut-out of FIG. 2;

FIG. 4 is a longitudinal section through an arrangement of a guidesleeve and of a coupling sleeve in the injection device of FIG. 1A;

FIG. 5A is a top view onto a ball bearing ring;

FIG. 5B is a sectional view of the ball bearing ring in the plane A-A;

FIG. 6 is a perspective view of a coupling sleeve;

FIG. 7 is a longitudinal section through selected parts of the injectiondevice of FIG. 1A;

FIG. 8 is a perspective illustration of a bayonet sleeve;

FIG. 9A is a top view onto a bayonet spring;

FIG. 9B is a side view of the bayonet spring of FIG. 9A;

FIG. 9C is a perspective view of the bayonet spring of FIG. 9A;

FIG. 10 is a longitudinal section through selected parts of theinjection device of FIG. 1A;

FIG. 11A is a longitudinal section through selected parts of theinjection device of FIG. 1A with a dose limiting ring in its finalposition;

FIG. 11B is a longitudinal section through selected parts of theinjection device of FIG. 1A with the dose limiting ring in its initialposition;

FIG. 12A is a perspective view of a coupling shaft with a dose limitingring of the injection device of FIG. 1A;

FIG. 12B is the parts of FIG. 12A in an exploded view;

FIG. 12C is the coupling shaft of FIG. 12A in a perspective view fromanother direction of view;

FIG. 13 is an exploded view of an arresting sleeve, a coupling springand a support ring;

FIG. 14 is a perspective view of selected parts of the injection deviceof FIG. 1A;

FIG. 15 is a perspective exploded view of the proximal end of theinjection device of FIG. 1A;

FIG. 16 is a longitudinal section through the injection device of FIG.1A in the initial position;

FIG. 17 is the longitudinal section of FIG. 16 after a first increase ofdose up to half the maximum dose;

FIG. 18 is the longitudinal section of FIG. 16 after a first increase ofdose up to the full maximum dose;

FIG. 19 is the longitudinal section of FIG. 16 after a first triggeringand a second increase of dose;

FIG. 20 is a longitudinal section through the injection device of FIG.1A after a complete emptying of the carpule;

FIG. 21 is a longitudinal section through an injection device accordingto another embodiment.

DETAILED DESCRIPTION

With regard to fastening, mounting, attaching or connecting componentsof the present invention, unless specifically described as otherwise,conventional mechanical fasteners and methods may be used. Otherappropriate fastening or attachment methods include adhesives, weldingand soldering, the latter particularly with regard to the electricalsystem of the invention, if any. In embodiments with electrical featuresor components, suitable electrical components and circuitry, wires,wireless components, chips, boards, microprocessors, inputs, outputs,displays, control components, etc. may be used. Generally, unlessotherwise indicated, the materials for making the invention and/or itscomponents may be selected from appropriate materials such as metal,metallic alloys, ceramics, plastics, etc. Generally, unless otherwiseindicated, relative positional or orientational terms (e.g., upwardly,downwardly, above, below, etc.) are intended to be descriptive, notlimiting.

FIG. 1A depicts an injection device in the form of an injection pen in aperspective exploded view. FIG. 2 shows the device in longitudinalsection. The following description relates to the device in theassembled state, as is illustrated in FIG. 2.

The injection device has a housing sleeve 20 in which a mechanism ishoused for setting and distributing a dose. The housing sleeve 20 hassubstantially the form of a circular cylinder and defines a longitudinalaxis. A receptacle holder in the form of a carpule sleeve 30 isdetachably fastened to a distal end of the housing sleeve 20 by abayonet connection, which is described in further detail below. Thisreceives a receptacle in the form of a carpule 40 with a fluidmedicament, in which a stopper 41 is displaceably guided. A medicamentreservoir R of changeable volume is thereby delimited inside thecarpule. Instead of a carpule, a different receptacle can also bepresent, the volume of which is changeable, e.g., a receptacle withwalls folded in a concertina-like manner in the manner of a bellows. Thecontent of the carpule 40 may be monitored through an elongated viewingwindow 34 in the carpule sleeve 30. A needle holder 31 is screwed on thedistal end of the carpule sleeve 30, which needle holder 31 carries ahollow needle (cannula) 32, serving as injection needle, the proximalend of which projects through a sealing septum into the medicamentreservoir R. A removable needle protection sleeve 33 surrounds theforwardly projecting region of the needle 32 and protects a user frombeing pricked accidentally. A protective sleeve 10, the distal end ofwhich is permanently closed by a protective cap 50, is pushed over thecarpule sleeve 30. A holding ring 11 with detent arms 12 extending inthe proximal direction is mounted inside the protective sleeve 10. Theends of the detent arms 12 are detachably engaged with the carpulesleeve 30. The proposed embodiments are described here by an injectiondevice which has a needle 32, but it is also conceivable that theinjection device has several needles or no needle, as in a jet injector.

At the proximal end of the housing sleeve 20, a dosing sleeve 60 isrotatably arranged with a push button 80 held therein. The dosing sleeveserves for the setting of a dose, which is to be distributed from themedicament reservoir R, and for the tensioning of a drive arrangementwith a drive element in the form of a spiral spring 310, acting as atorsion spring. The set dose is displayed on a display drum 70, and canbe read through a window 21 in the housing sleeve 20, which is coveredby a transparent covering 22. A correcting (reduction) of the set dosemay be possible by turning back the dosing sleeve 60, which is describedin further detail below.

With reference to these parts, the following directions can be defined,which will be referred to consistently below: The distal (forward)direction is the direction in which the administering takes place, i.e.,it points along the longitudinal axis from the push button 80 in thedirection of the hollow needle 32. The proximal (rearward) direction isaccordingly defined as the opposite direction. If reference is made to adirection of rotation (clockwise, anticlockwise), this means thedirection of rotation which one observes when one views along thelongitudinal axis in the distal direction.

After the setting of the dose, the hollow needle 32 is pierced throughthe skin of the patient, and a distribution of the dose is triggered bythe user pushing the push button 80 into the dosing sleeve 60. A rotarymovement is produced by the drive arrangement via a mechanism, which isdescribed in detail below, this rotary movement being converted into anadvancing of a delivery element in the form of a thrust sleeve 90 in thedistal direction. The thrust sleeve 90 pushes the stopper 41 of themedicament carpule 40 by the set amount in the distal direction via athrust flange 100 arranged at its distal end, whereby the distributionof the medicament is brought about out of the reservoir R. The thrustsleeve 90 therefore acts as a piston rod for the piston which is formedby the thrust flange 100 and the stopper 41. After the end of theadministering, the user releases the push button 80 again. During theadvance of the thrust sleeve 90, the display drum is entrained by thedrive arrangement such that it returns to its zero position in thecourse of the distribution. The injection pen is thereby immediatelyready for the next dose setting.

When the medicament or therapeutic substance in the medicament reservoirR is running low, i.e. the thrust sleeve 90 is almost completelyextended, this is detected by a dose limiting arrangement in theinjection pen, which is described in further detail below. The doselimiting arrangement allows the user to set as a maximum the remainingavailable residual dose. In a subsequent carpule or ampuole change, thedose limiting arrangement and also the display drum 70 automaticallyreturn into the initial state, and manual resetting may be unnecessary.

The structure and mode of operation of the mechanism are described indetail below.

FIG. 3 shows an enlarged illustration of the rear (proximal) region ofthe injection device of FIG. 1A. The structure of this region will nowbe described in detail substantially from the interior outwardly.

The thrust sleeve 90 is mounted in a guide sleeve 110, arranged suchthat it is locked against relative rotation with respect to the housingand displaceably, locked against relative rotation and displaceably inthe longitudinal direction. For this, the thrust sleeve 90 has, at itsproximal end, several radially outwardly projecting guide cams 91, whichare guided in longitudinal grooves, complementary thereto, on the innerside of the guide sleeve 110.

The guide sleeve 110 can be seen in FIG. 4, which illustrates thecooperation of the guide sleeve 110 with further parts. The guide sleeve110 has at its distal end a radially outwardly projecting,circumferential ring flange 111 with radial bores 112. A ring-shapedbearing holder 130 is pushed from the proximal side via the guide sleeve110, surrounds the ring flange 111 radially and is connected rigidlytherewith via radial cylinder pins, which are not illustrated in thedrawings.

A coupling sleeve 120 is rotatably mounted between the ring flange 111of the guide sleeve 110 and an inwardly projecting shoulder 132 of thebearing holder 130. As is described in further detail below, thecoupling sleeve 120 is connected via a threaded rod 180 with the thrustsleeve 90 and therefore forms a part of a delivery arrangement, which isdriven by a rotary movement and brings about a thrust of the deliveryelement in the form of the thrust sleeve. The coupling sleeve 120therefore absorbs considerable axial forces in operation, which aretransmitted via its bearing onto the guide sleeve 110, the bearingholder 130, the mechanism holder 150 and therefore to the housing.

To construct the bearing so as to be low-loss, the bearing includes ballbearings for providing relatively low friction to a rotating unit.Accordingly, a first ball bearing ring 140 is provided between theflange 111 of the guide sleeve and a radially encircling flange 124 ofthe coupling sleeve 120. A further such ball bearing ring 140 isarranged between the flange 124 and an end face of the bearing holder130.

The ball bearing ring 140 is illustrated in detail in FIGS. 5A and 5B.It carries a plurality of bearing balls 141, i.e., twelve, but mayinclude a range of bearing balls such as from 3 to 24. The bearing balls141 run or roll, as can be seen in FIG. 3, in flat, circular groovesformed in both end faces of the radial flange 124 of the coupling sleeve120, in the corresponding end face of the flange 111 of the guide sleeve110 and in the end face of the bearing holder 130.

The coupling sleeve 120 is illustrated in FIG. 6, together with the ballbearing rings 140 (but without balls 141). On the cylindrical sleevebody 121, a plurality of longitudinal ribs 122 are formed, which extendover a considerable part of the length of the sleeve body in alongitudinal direction up to its proximal end. Corresponding grooves areprovided therebetween. From a thickening area 123, the flange 124follows towards the front, which adjoins the ball bearing rings 140 onboth sides.

FIG. 7 illustrates how the unit of guide sleeve 110 and bearing holder130 is held in a sleeve-shaped mechanism holder 150, so as to be lockedagainst relative rotation, but displaceably arranged in the longitudinaldirection.

The mechanism holder 150 includes a distal section 151 with increasedinternal and external diameter and a proximal section 152 with asomewhat smaller internal and external diameter. These two sections areconnected by a step 153. The outer side of the distal section 151 isheld rigidly in the housing sleeve 20. Thereby, the mechanism holder 150may be immovable with respect to the housing, therefore formingfunctionally a part of the housing.

Adjoining the step 153, at least two longitudinal slits 154 are formedin the mechanism holder 150. Pins, which are not illustrated in FIG. 7,are inserted in the bearing holder 130. These project radially beyondthe bearing holder 130 and into the longitudinal slits 154 of themechanism holder. The bearing holder 130 and the guide sleeve 110, whichis securely connected therewith, may thus be guided displaceably betweena distal and a proximal final position and so as to be secured withregard to rotation in the mechanism holder 150. Toward the proximal end,on the outer covering surface of the mechanism holder 150, an externalthread 157 is formed. Several longitudinal grooves 158 are formed inthis region on the inner surface.

In the distal direction, a bayonet sleeve 160 adjoins the guide sleeve110 and the bearing holder 130, which is also illustrated in FIG. 8. Itis held on the bearing holder 130 in the axial direction and isrotatable with respect thereto. With an inwardly projecting ring flange161, the bayonet sleeve 160 supports the unit of guide sleeve 110 andbearing holder 130, with coupling sleeve 120 held therein, in the distaldirection. The bayonet sleeve 160 has two arms 162 projecting axially inthe distal direction and lying diametrically opposite each other, whicharms 162 have radial openings 163. Radially outwardly projecting pinsare inserted into these openings, which pins run in two guide slits 155of the mechanism holder 150 acting as connecting link guides (positiveguides). Guide slits 155 are configured so that the bayonet sleeve 160,with an anticlockwise rotation (in the sense of the definition indicatedabove, i.e., on observation along the longitudinal axis in the distaldirection) is compulsorily also moved axially in the proximal direction.In this way, the unit of guide sleeve 110, bearing holder 130 andcoupling sleeve 120 is moved in the proximal direction. Vice versa, witha rotation of the bayonet sleeve 160 clockwise, this unit moves in thedistal direction. Parallel to the guide slits 155, a further pair ofguide slits 156 runs, in order to receive radial pins 36 of a lockingregion 35 of the carpule sleeve 30 (cf. FIGS. 1 and 3). On introductionof the carpule sleeve 30 into the housing, the carpule sleeve is alsosubject to a positive guidance, so that the carpule sleeve 30 performs acombined rotary movement and displacement. The carpule sleeve 30 isconfigured such that, upon its movement, it is coupled with the arms 162of the bayonet sleeve 160 and entrains the bayonet sleeve 160.

The guide slits 155 are of finite length and delimit the movement of thebayonet sleeve between a distal and a proximal final position. In FIG.7, the proximal final position is illustrated in which the guide slits155 allow a rotation of the bayonet sleeve through 90 degrees betweenthese positions.

To fix the bayonet sleeve detachably in its two final positions so as tobe locked against relative rotation with respect to the guide sleeve110, and thus with respect to the housing sleeve 20, a bayonet spring170 is arranged between the bayonet sleeve 160 and the guide sleeve 110.This is illustrated, in detail, in FIGS. 9A to 9C. The bayonet spring170 has a substantially flat and ring-shaped base body 171 acting as aspring element. Two diametrically opposite, axially flatly projectingbulges or projections 172 protrude out from this base body as detentelements or detent cams axially in the distal direction. Twodiametrically opposite flat tongues 173 protrude inwardly and come tolie in corresponding flat recesses of the guide sleeve 110. Thereby, thebayonet spring 170 is held, so as to be secured with regard to torsion,on the guide sleeve 110. As can be seen from FIG. 9B, the base body 171is bent slightly about an axis perpendicular to the longitudinal axis,and namely such that the curvature mid-point lies on the same side ofthe bayonet spring as the projections 172 (i.e., distal). As a result,the bayonet spring 170 is pre-stressed between the guide sleeve 110 andthe bayonet sleeve 160 permanently such that the projections 172 arepressed in the distal direction against the correspondingcounter-surface on the ring flange 161. In this counter-surface, fourdepressions are present, which are arranged at intervals of 90 degreesabout the longitudinal axis. In the proximal final position, theprojections 172 come to lie in a first pair of these depressions,whereas in the distal final position, in which the bayonet sleeve isturned through 90 degrees, they are held in the second pair of thedepressions. Thereby, two defined detent positions are provided, inwhich the bayonet sleeve 160 engages via the bayonet spring 170 with theprojections 172 detachably with the guide sleeve 110. In both positions,a certain force may need to be overcome to move the bayonet sleeve inthe direction of the respective other final position again. Each of thedepression pairs may comprise a different configuration, e.g., depthand/or shape, so that a different releasing force is necessary in thetwo detent positions.

In one detent position, the carpule sleeve 30 is held via its couplingwith the bayonet sleeve 160 to be secure with regard to rotation anddisplacement on the guide sleeve 110, and thus on the housing. In theother detent position, the carpule sleeve 30 is detached from thehousing. In this position, the bayonet sleeve 160 is again engaged withthe guide sleeve 110 and is thereby fixed on the housing 20 so as to besecure with regard to rotation and displacement. In this way, thecarpule sleeve, on insertion into the guide slits 156, locates the arms162 of the bayonet sleeve in the correct position around thelongitudinal axis, and can entrain these upon the releasing of thedetent connection.

In the present example, the detent elements are constructed asprojections 172 integrally formed with the spring element in the form ofthe base body 171. Alternatively, a separate detent element may beprovided, e.g., in the form of a rigid ring with detent cams, which maybe pressed in the axial direction by the spring element. As an alternateto projections, the detent element may also have depressions, which thencooperate with corresponding projections of the counter surface. In thepresent example, the detent element is locked against relative rotationwith respect to the housing. Alternatively, it can also be lockedagainst relative rotation with respect to the bayonet sleeve. The springelement may also have an alternative configuration to produce an axialforce. Accordingly, various modifications of locking between the carpulesleeve 30 and the housing are contemplated.

In FIG. 10, the parts of the injection device illustrated in FIG. 7 areillustrated together with the thrust sleeve 90 arranged in the guidesleeve 110. At its proximal end, the thrust sleeve 90 has a shortinternal thread 92 in which a hollow external threaded rod 180 isguided. The latter is connected at its proximal end rigidly with thecoupling sleeve 120 via a transverse pin 181. A thrust of the thrustsleeve 90 in the distal direction takes place, by the coupling sleeve120, which is rotatably mounted, carrying out a rotary movement. As aresult of the rigid connection between coupling sleeve 120 and externalthreaded rod 180, this rotary movement also brings about a rotation ofthe external threaded rod 180. The thrust sleeve 90 runs with itsinternal thread 92 on the external threaded rod 180, similar to a nut.The thrust sleeve 90 is locked against relative rotation with respect tothe guide sleeve 110, because it runs via the guide cams 91 inlongitudinal grooves on the inner side of the guide sleeve 110. In thisway, the thrust sleeve 90 is advanced axially on a rotation of theexternal threaded rod 180. Accordingly, a rotary movement of thecoupling sleeve 120 is converted into an axial displacement of thethrust sleeve 90.

As can be seen from FIG. 3, the thrust sleeve 90 is assisted in thisthrust movement by a long helical spring 190, which is subjected topressure, and which is arranged in the interior of the threaded rod 180and is guided on a guide needle 200. The helical spring 190 presses aring-shaped thickening 201 close to the distal end of the guide needle200 in the distal direction against the thrust flange 100. An axial pin202 projects into a corresponding blind-end bore of the thrust flange100 and is rotatable in this blind-end bore.

Furthermore, in FIG. 10 a substantially cylindrical transmission sleeve210 is inserted into the mechanism holder 150 from the proximal side,which transmission sleeve partially surrounds the coupling sleeve 120.The transmission sleeve 210 has on the outer side a plurality oflongitudinal ribs 212. The external diameter of the transmission sleeve210 is selected here so that, despite its external longitudinal ribs, itis freely rotatable inside the mechanism holder 150. On the inner side,the transmission sleeve 210 has an internal thread 211, in which a doselimiting ring 220 runs with a corresponding external thread 221. In theinterior of the dose limiting ring 220, longitudinal grooves 222 arepresent which can be seen in FIGS. 12A and 12B, into which thelongitudinal ribs 122 of the coupling sleeve 120 (cf. FIG. 6) engage.Thereby, the dose limiting ring 220 is movable on the one hand so as tobe secure with regard to rotation in the axial direction on the couplingsleeve, and on the other hand is guided in the internal thread of thetransmission sleeve 210. A rotation of the coupling sleeve 120 withrespect to the transmission sleeve 210 therefore leads to a rotation andaxial displacement of the dose limiting ring 220.

The axial displacement range of the dose limiting ring is limited in thedistal and proximal directions. This is described in conjunction withFIGS. 11A, 11B, 12A and 12B.

In FIGS. 11A and 11B, a coupling shaft 230 is connected with thetransmission sleeve 210. The coupling shaft comprises an axis 231 with atransverse bore 232 close to the proximal end 233. A circumferentialflange 234 extends radially outwardly from the distal end of the axis. Aring flange 235 extends in turn therefrom axially in the distaldirection. The external diameter of the circumferential flange 234 isgreater than that of the ring flange 235, whereby the circumferentialflange 234 protrudes radially over the ring flange 235, and forms a stopfor the transmission sleeve 210. The ring flange 235 is pushed into thetransmission sleeve 210, so that the latter lies with its proximal endagainst the circumferential flange 234. The ring flange is secured byradial pins in the transmission sleeve 210, which are pushed into bores237. Thereby, the coupling shaft 230 and the transmission sleeve 210 areconnected with each other so as to be locked against relative rotationand secured against displacement. Several longitudinal grooves 238 areformed in the inner surface of the ring flange 235.

FIGS. 12A and 12B show the coupling shaft 230 and the dose limiting ring220 alone. A radial stop 223, which cooperates with a correspondingradial stop 236 on the ring flange 235 of the coupling shaft, is formedon the dose limiting ring 220. A radial stop is understood to mean astop surface, the surface normal of which points substantially in thetangential direction, and which is formed to cooperate with acorresponding counter surface. The radial stop is therefore primarilystressed in a tangential direction (i.e., in a rotational direction)instead of in an axial direction. Thereby, a radial stop avoids the riskof jamming, such as when two parts collide axially via a screwconnection, e.g., in the case of a small pitch of the helical thread.The radial stop 236 delimits the screw motion of the dose limiting ring220 in the proximal direction. In FIG. 11A the dose limiting ring 220 isshown in the resulting proximal final position, and in FIG. 11B on theother hand in a distal initial position.

The proximal end of an arresting sleeve 280 is rotatably clicked into aninwardly directed ring flange 213, chamfered in the distal direction, atthe distal end of the transmission sleeve 210. For better clarity, thearresting sleeve 280 is not illustrated in FIG. 10. However, it is shownin FIG. 13. The arresting sleeve comprises a ring-shaped main body 281,from which four arms 282 extend in the distal direction. On its innersurface, the main body has longitudinal grooves 284, which are meshedwith the longitudinal ribs 122 of the coupling sleeve 120. Thereby, thearresting sleeve 280 is displaceable in the longitudinal directionrelative to the coupling sleeve 120, but is secured as regards torsionwith respect thereto. At the end of the arms 282, inwardly extendingflange regions 283 are present. The possible displacement range islimited in the proximal direction by these flange regions. These abut inthe proximal final position of the arresting sleeve 280, as illustratedin FIG. 3, onto the distal end of the longitudinal ribs 122 of thecoupling sleeve 120. Longitudinal ribs are formed on the outerperipheral surface of the main body 281. These longitudinal ribs engage,in the position of FIG. 3, into the inner longitudinal grooves 158 ofthe mechanism holder 150. Thereby, the arresting sleeve 280 isdisplaceable in this position axially with respect to the mechanismholder 150, but secured with regard to torsion. The arresting sleeve 280in this position therefore secures the coupling sleeve 120 against arotation in the mechanism holder 150. As described further below, thearresting sleeve 280 is, however, displaceable so far in the distaldirection that it can come out of engagement with the mechanism holder150 and is then rotatable with the coupling sleeve 120.

The arresting sleeve 280 is pre-stressed in the proximal direction by acoupling spring 290. The coupling spring is configured as a helicalspring, which is subjected to pressure, surrounds the arms 282 of thearresting sleeve 280 and lies with its proximal end against the distalend face of the main body 281. At the distal end of the coupling spring290, the latter is held on a support ring 300, which abuts against thebearing holder 130 in the distal direction and on the inner side ofwhich longitudinal grooves are formed.

In FIG. 14, the unit of FIG. 10 is illustrated with further components.The display drum 70 is held on the mechanism holder 150. In addition, astop sleeve 240 is connected immovably with the housing sleeve 20 bypins projecting into the radial holes 242, e.g., see FIG. 14. At thedistal end of stop sleeve 240, radial stops 243 are provided, and at theproximal end, teeth 244, e.g., serrated teeth, are arranged on the endface for a ratchet connection, described below.

The display drum 70 has an internal thread, which can be seen in FIG. 3,and runs on the external thread 157 of the mechanism holder, which canbe seen in FIGS. 7 and 10. At its proximal end, the display drum 70narrows to a ring-shaped region 72. Longitudinal grooves are formed onthe inner side of the ring-shaped region 72. By these longitudinalgrooves, the display drum 70 is secured with regard to torsion, but isguided displaceably in the longitudinal direction on the longitudinalribs 212 of the transmission sleeve 210. Through the combination of thislongitudinal guide on the transmission sleeve and the thread guide onthe mechanism holder, a rotation of the transmission sleeve 210 leads toa combined rotation and longitudinal displacement of the display drum70. This movement is delimited or stopped by radial stops in bothdirections. At the proximal end, a radial stop cooperates with theradial stop 243 of the stop sleeve 240. At the distal end, acorresponding radial stop 73 cooperates with a radial stop 159 of themechanism holder 150. Thereby, the screw motion of the display drum 70is limited in both directions by radial stops.

The mechanism for setting a dose and for triggering its administering isdescribed with reference to FIGS. 3 and 15. The dosing sleeve 60 isarranged at the proximal end of the housing sleeve 20. Dosing sleeve 60is secured with regard to displacement axially with a spring ring 61 andis fixed rotatably on the stop sleeve 240. The dosing sleeve 60 isrotatable via a slip coupling in the form of a ratchet connection bothclockwise and also anticlockwise about the longitudinal axis towards thehousing sleeve 20, and is thus configured and arranged to assume severalpredefined detent positions.

The dose setting mechanism comprises an inner ring 250 arranged insidethe dosing sleeve 60 and rigidly connected with the dosing sleeve 60.The inner ring 250 has in its radial inner surface a plurality oflongitudinal grooves. In the distal direction from the inner ring 250, aratchet ring 260 is held axially displaceably but secured with regard torotation in the dosing sleeve 60. The ratchet ring 260 is serrated onits distal end face, and namely in a complementary manner to the teeth244 of the serrated proximal end face of the stop sleeve 240, so thatteeth of the ratchet ring 260 can engage in depressions on the end faceof the stop sleeve 240 and vice versa. The ratchet ring 260 is axiallydisplaceable by a certain amount between the distal end face of theinner ring 250 and the serrated proximal end face of the stop sleeve240. The amount by which an axial displacement is such that the serratedend faces of the ratchet ring 260 and of the stop sleeve 240 can comeout of engagement. The ratchet ring 260 is pressed elastically by anelastic force against the stop sleeve 240. For this, several axial bores251 are present in the form of blind-end bores in the inner ring 250.Helical springs 252, which are subjected to pressure are inserted in atleast one of these bores, e.g., in at least two bores, at a uniformspacing along the circumference of the ring when multiple bores areprovided. The helical springs 252 press the ratchet ring elasticallyagainst the stop sleeve.

In the position of rest, the ratchet ring 260, with its serrated endface, is in engagement with the serrated end face of the stop sleeve240. Thereby, the ratchet ring and the dosing sleeve 60 connectedtherewith assume one of several defined angle positions about thelongitudinal axis. With a rotation of the dosing sleeve 60 relative tothe housing sleeve 20, the teeth of the ratchet ring 260 and of the stopsleeve 240 slide on each other against the axial spring force of thehelical springs 252, until they come out of engagement and arrive inengagement again in the next defined angle position. In this way, anelastically detachable detent connection is produced by rotation with asufficient torque in several predefined angle positions of the dosingsleeve 60 relative to the housing sleeve 20. This mechanism can also bedesignated as a double slip coupling.

By rotation of the dosing sleeve 60 clockwise, the spiral spring 310 canbe tensioned, which is indicated in FIG. 3. The spiral spring 310 has aplurality of spring coils, which run around the longitudinal axis andare arranged over one another radially to the longitudinal axis. Theinner end of the spiral spring 310 is fastened to a spring holdingregion 311 of the coupling shaft 230, which region can be seen in FIG.12C. The outer end of the spiral spring 310 is mounted on a springsleeve 320, which is held so as to be locked against relative rotationin the stop sleeve 240.

A coupling disc 270 is mounted on the coupling shaft 230, and is securedagainst rotation and displacement by a pin 271 in the transverse bore232 of the coupling shaft 230. The coupling disc 270 has a plurality oflongitudinal ribs on its outer peripheral surface. In the position ofFIG. 3, these longitudinal ribs engage into the longitudinal grooves,which are complementary, on the inner side of the inner ring 250, butcan be brought out of engagement by an axial displacement.

The dosing sleeve 60 has an axial passage opening, in which the pushbutton 80 is arranged so as to be axially displaceable. The push button80 is rotatable with a plurality of radially elastic arms 81 and isclicked on the proximal end 233 of the coupling shaft 230 so as to besecured against displacement. It abuts with its distal end against aproximal end face of the coupling disc 270. In the interior of the pushbutton 80 there is a helical spring 82, which lies with its proximal endagainst the inner end face of the push button and presses with itsdistal end against a bearing ring 83. The bearing ring 83 has on itsouter peripheral face longitudinal ribs, which are guided incorresponding longitudinal grooves in the inner covering surface of thepush button 80. Thereby, the support ring 83 is arranged in the pushbutton 80 so as to be locked against relative rotation and so as to beaxially displaceable. The bearing ring 83 is configured be serrated in aflat manner on its distal end face. The proximal end face of thecoupling disc 270 is formed so as to be serrated in a complementarymanner hereto, so that the bearing ring 83 is axially meshed with thecoupling disc 270. On distribution of the medicament, the coupling disc270 rotates with respect to the bearing ring 83. Thereby, the serratedsurfaces slide on one another, so that the toothing comes alternatelyinto and out of engagement. Thereby, a characteristic clicking sound isproduced, which indicates to the user that an administering is justtaking place. The toothing of bearing ring 83 and coupling disc 270 maybe configured so that each clicking corresponds to one unit, or of apredetermined multiple of one unit, of the administered medicament.

The mechanism for setting the dose and the distribution may be arrangedand configured in the housing sleeve 20 so as to be protected againstsplashing, i.e., sealed. According to certain embodiments, four sealsD1, D2, D3 and D4 may be provided. The seal D1 comprises a sealing ring,which lies in a sealing manner between the mechanism holder 150 and thebayonet sleeve 160. The mechanism holder 150 is mounted immovably andtightly in the housing 2, and the bayonet sleeve 160 is bothdisplaceable and rotatable with respect to the mechanism holder 160 andis sealed with respect to the housing by the seal D1.

The seal D2 comprises a further sealing ring, constructed so as to beflat, which lies in a sealing manner between the bayonet sleeve 160 andthe smooth outer side of the thrust sleeve 90. Thrust sleeve 90 may havea smooth (e.g., within accepted and/or manufacturing tolerances) orsubstantially smooth outer wall region, the length of which correspondsat least to the distance between the distal final position and theproximal initial position of its longitudinal movement, between whichthe thrust sleeve 90 is movable in the course of the administering. Thesealing effect between seal D2 and thrust sleeve 90 may be facilitatedby providing an outer wall region of the thrust sleeve 90 with finestructures, e.g. scales, a pattern or texture, in the range below 100micrometers, e.g. below 10 micrometers, and may be configured as micro-or nano-structuring, at least along the length between the distal finalposition and the proximal initial position. A thrust sleeve 90 with suchmicro- or nano-structuring may be considered substantially smooth to oneof skill in the art due to the minute size of the structures. However,one of skill in the relevant art would also appreciate the usefulness ofsuch structures in maintaining and/or enhancing a seal between thethrust sleeve 90 and seal D2. In some embodiments, the outer wall regionmay extend from thrust flange 100 to guide cams 91. In addition, textureor structure provided on the substantially smooth surface may extendalong the entire outer wall region or along portions thereof. Texture 93along the thrust sleeve is depicted in FIG. 1B, which is configured asmicro-structured scales. In addition or alternatively, other structures,such as surface protrusions or indentations, which may have a desiredtexture or structure, may be provided along the outer wall region. Suchadditional or alternative structures may have an orientation such thatthe structures are directed towards the proximal or distal direction.Furthermore, the thrust flange 100 is arranged tightly on the thrustsleeve 90. The region of the injection device, including the interior ofthe thrust sleeve 90, lying proximally from the bayonet sleeve 160, maythus be sealed against the region lying distally. Where fluids areintroduced into this distal region, e.g., due to a breakage of themedicament carpule 40, the fluid may be prevented from penetrating intothe mechanics, thus preventing contamination or jamming.

The other two seals are situated at the proximal end of the injectiondevice. The seal D3 comprises a sealing ring, which lies in a sealingmanner between the dosing sleeve 60 and the stop sleeve 240. The stopsleeve 240 is mounted immovably and tightly in the housing sleeve 20,whereas the dosing sleeve 60 is rotatable with respect to the stopsleeve 240. The seal D4 comprises a further sealing ring, which lies ina sealing manner between the dosing sleeve 60 and the push button 80. Inaddition, a transparent window covering 22 is placed in a fluid-tightmanner on the window 21. Accordingly, mechanisms, operational componentsor mechanics, which are delimited toward the exterior by the housingsleeve 20, the dosing sleeve 60 and the push button 80, are also sealedtoward the exterior and may be protected against the penetration offluids. Rainfall or a glass of water accidentally spilt by the user cantherefore also not harm the injection device.

The seal towards the thrust sleeve may be configured such that it actsas a stripper, similar to a windshield wiper in a car. For this, atleast towards the distal side, there is as small a contact angle betweenthe surfaces of the sealing element and the thrust sleeve, which may liebelow 90 degrees.

Instead of conventional seals or in addition hereto, the parts which areto be sealed with respect to each other may be configured with ahydrophobic surface, such as being formed of or coated with ahydrophobic material. A hydrophobic surface may prevent the parts frombeing wetted. Drops of water thereby roll off and a leaking of fluidsthrough gaps is efficiently prevented between the parts, which are to besealed due to capillary effects. The parts provided with a hydrophobicsurface, which are to be sealed with respect to each other, maytherefore be arranged at a certain distance (gap) from each other,without the sealing effect being lost (“virtual seal”).

A hydrophobic surface is understood here to mean a surface for which thecontact angle of a water drop is at least 90 degrees, e.g., at least 110degrees. The contact angle is the angle between the surface normal ofthe water drop and the respective surface at the contact site. Examplesof materials with hydrophobic characteristics are PTFE(polytetrafluoroethylene) or PVDF (polyvinylidene fluoride), as well asother hydrophobic materials that may be formed as thin coatings, e.g.,in the range of a few micrometers, to provide a hydrophobic surface.

In experiments, various pens and a sleeve were providednanotechnologically with a hydrophobic coating. 20 pens with externaldiameters of 10.0 to 11.9 mm in graduations of 0.1 mm were examined. Thepens were arranged centrally in a sleeve with 12 mm internal diameter,which corresponds to gap thicknesses of 0.05 mm to 1.0 mm in graduationsof 0.05 mm. The interior of the sleeve was then acted upon with water. Asealing effect up to a gap thickness of approximately 0.5 mm wasobserved. With reciprocal rotation between pen and sleeve, a sealingeffect up to a gap thickness of approximately 0.25 mm was observed.

To improve the sealing effect, the surfaces may be micro- ornano-structured, i.e., provided with structures, the dimensions of whichare in the nanometer to micrometer range. These structures can have aselected direction, to inhibit the flow of fluids on the surface in onedirection. Thus, for example, scales can be provided.

The mode of operation of the injection device is now to be describedbelow with reference to FIG. 16, in which an exemplary injection deviceis illustrated in its initial position before the first use. Themechanism described above for setting and distributing a dose has threecouplings K1, K2 and K3 for the transmission of torques. Each of thesecouplings may be brought into and out of engagement by an axial movementof two components with respect to each other.

The coupling K1 is formed by the longitudinal grooves on the innersurface of the axial flange 235 of the coupling shaft 230 as a couplinginput member in cooperation with the longitudinal ribs 122 on the outerside of the coupling sleeve 120 (cf. FIG. 5) as coupling output member.In the position of FIG. 16, this coupling is uncoupled, i.e., thecoupling formed by the cooperation of the longitudinal grooves andlongitudinal ribs is out of engagement. The coupling K1 can be coupledby an axial displacement of the coupling shaft 230 in the distaldirection.

The coupling K2 is formed by the longitudinal grooves in the radialinner surface of the inner ring 250 as a coupling input member incooperation with the longitudinal ribs on the radial outer surface ofthe coupling disc 270 as coupling output member. In the position of FIG.16, this coupling is coupled, i.e., the toothing formed by thelongitudinal grooves and longitudinal ribs is in engagement. Thecoupling K2 can be uncoupled by an axial displacement of the couplingdisc 270 in the distal direction.

The coupling K3 is formed by the longitudinal ribs on the outer side ofthe outer ring flange arms 282 of the arresting sleeve 280 as couplinginput member in cooperation with the longitudinal grooves 158 on theinner surface of the mechanism holder 150 as coupling output member. Inthe position of FIG. 13, this coupling is coupled. It can be uncoupledby an axial displacement of the arresting sleeve 280 in the distaldirection.

All three couplings K1, K2 and K3 can be coupled and respectivelyuncoupled by the push button 80 being displaced axially. On pressing inof the push button 80, the coupling disc 270 and the coupling shaft 230,which is securely connected therewith, are displaced in the distaldirection. In this instance, the coupling K1 comes into engagement,i.e., the coupling shaft is coupled for torque transmission with thecoupling sleeve 120. At the same time, the coupling shaft 230 advancesthe transmission sleeve 210 in the distal direction. This entrains thearresting sleeve 280 in the distal direction, whereby the couplingspring 290 is compressed. When the coupling K1 arrives in engagement forthe first time, the arresting sleeve 280 is not yet advancedsufficiently far to arrive with its outer ring flange arms 282 out ofengagement with the mechanism holder 250. The coupling K3 is thereforeinitially still coupled. The same applies to the coupling K2: Thecoupling disc 270 is still in engagement with the inner ring 250.Therefore, all three couplings are coupled. When the push button 80 ispushed in further, the coupling K2 comes out of engagement. With a stillfurther pushing in, coupling K3 comes out of engagement. Therefore, thecouplings are as follows: Initial state: K1 uncoupled, K2 and K3coupled. Pushing in of the push button 80: K1 couples, thereafter K2uncouples, thereafter K3 uncouples.

FIG. 19, described further below, shows the injection device with thepush button 80 pushed in completely. The coupling K1 is coupled, whereasthe couplings K2 and K3 are uncoupled.

On releasing of the push button 80, the engaging of the couplings intoeach other runs in the reverse sequence. Here, the coupling spring 290presses the arresting sleeve 280, the transmission sleeve 210, thecoupling shaft 230, the coupling disc 270 and the push button 80 backinto the distal initial position.

The couplings K1, K2 and K3 and the ratchet connection make possible thesystematic transmission of torques between five functionally independentunits. A first unit comprises the housing sleeve 20, the mechanismholder 150, the stop sleeve 240 and the spring ring 320. This unit canbe regarded functionally as a holding arrangement or as a housing in anextended sense. It constitutes the stationary reference system for allmovements.

A second unit comprises the dosing sleeve 60, the inner ring 250 and theratchet ring 260. It can be regarded functionally as a rotatable dosingarrangement. This dosing arrangement is held detachably on the housingby the ratchet connection, but so as to be secure with regard to torqueup to a certain value.

A third unit comprises the coupling disc 270, the coupling shaft 230 andthe transmission sleeve 210, which are rigidly connected with eachother, and by the spiral spring 310, connected therewith, which acts asthe actual drive element. This unit can be regarded as a drivearrangement. The rotary movement of the drive arrangement is limited bytwo limiting elements, which are both guided on the transmissionarrangement. The first limiting element is formed by the display drum70, which limits the range of movement of the drive arrangement in bothdirections, a dosing direction and a correction and distributiondirection. The second limiting element is formed by the dose limitingring 220, which limits the range of movement of the drive arrangement atleast in one direction, the dosing direction, independently of the firstlimiting element. The drive arrangement is able to be coupled detachablyby the coupling K2 so as to be locked against relative rotation withrespect to the dosing arrangement, which makes it possible to tensionthe drive element in the form of the spiral spring 310.

A fourth unit comprises the coupling sleeve 120 and the threaded rod180, which form a rigid unit, the elements on which these parts aremounted, namely the guide sleeve 110, the bearing holder 130 and theball bearing rings 140, and also the thrust sleeve 90. This unitconstitutes a delivery arrangement, which converts a rotary movement ofan input member in the form of the coupling sleeve 120 into a thrust ofthe delivery element in the form of the thrust sleeve 90. Its inputmember is able to be detachably coupled by the coupling K1 so as to belocked against relative rotation with the drive arrangement. Inaddition, it is able to be detachably coupled via the coupling K3 so asto be locked against relative rotation with the holding arrangement(i.e., the housing).

Furthermore, a triggering arrangement is present, which comprises thepush button 80 and serves for the operation of the couplings K1 to K3.

The injection device is operated as follows. Starting from the initialposition of FIG. 16, a dose is set, which is to be administered. Forthis, the dosing sleeve 60 is turned clockwise. In so doing, the dosingsleeve entrains the coupling disc 270 and the coupling shaft 230 via thecoupling K2, and the spiral spring 310 is wound up. The torque generatedis held by the ratchet connection between the co-rotating ratchet ring260 and the stationary stop sleeve 240. Through the rotation of thecoupling shaft 230, the transmission sleeve 210 and the display drum 70,which is guided thereon, are also co-rotated. The display drum 70,threadably guided on the mechanism holder 150, is additionally displacedaxially in the proximal direction, and therefore performs as a whole ascrew motion in the proximal direction. Markings on the surface of thedisplay drum 70 pass through under the window 21 and indicate the setdose. Furthermore, the dose limiting ring 220, threadably engaged withthe interior of the transmission sleeve 210 and arranged, secured withregard to rotation, on the coupling sleeve 120, is displaced in theproximal direction.

FIG. 17 shows the injection device after half the maximum individualdose has been set. The display drum has travelled rearwardly half-waybetween its distal (forward) and its proximal (rear) final position. Inaddition, the dose limiting ring 220 has travelled in the proximaldirection by an amount proportional to the individual dose that has beenset.

The rotation of the dosing sleeve 60 clockwise is limited, on the onehand, by the maximum movement range of the display drum 70, and on theother hand, by the maximum movement range of the dose limiting ring 220.After a predetermined number of revolutions of the dosing sleeve 60, thedisplay drum 70 abuts with its proximal radial stop against the stopsleeve 240, in so far as the rotation of the dosing sleeve 60 has notbeen previously limited by the dose limiting ring 220, as is describedfurther below. Thereby, no further rotation of the dosing sleeve 60 ispossible. This position corresponds to the maximum individual dose,which can be set. This situation is illustrated in FIG. 18.

If the set dose is to be corrected, i.e., reduced, then the dosingsleeve 60 can be turned back anticlockwise against the force of theratchet connection. As the ratchet connection in this direction absorbsthe torque of the spiral spring 310, the ratchet connection isconfigured asymmetrically: The toothing on the end face has a largerangle of inclination on the side which is stressed by a torque whichacts anticlockwise onto the dosing sleeve than on the side which isstressed with a torque clockwise (cf. the configuration of the teeth 244in FIG. 14). The angle of inclination is understood here to mean theabsolute amount of the angle between the respective flank of a tooth onthe end face of the ratchet ring 260 or on the end face of the stopsleeve 240 and a cross-sectional area through the injector.

The distribution or delivery of the dose, which has been set is actuatedor initiated by the push button 80 being pushed in. In this instance,the coupling K1 is coupled, and a connection is produced which is lockedagainst relative rotation between the coupling shaft 230, on the onehand, and the coupling sleeve 120 and also the threaded rod 180 rigidlyconnected therewith, on the other hand. All three couplings K1, K2 andK3 are coupled. On further pushing in of the push button 80, thecoupling K2 uncouples. Thereby, the connection, which is locked againstrelative rotation between the dosing sleeve 60, on the one hand, and thecoupling shaft 230 with the coupled coupling sleeve 120 and threaded rod180, on the other hand, is cancelled. This leads to the ratchetconnection no longer absorbing the torque of the spiral spring 310.However, the system is held so as to be locked against relative rotationvia the coupling K2 in the mechanism holder 150 and hence in the housingsleeve 20. When the push button 80 is pressed further, the coupling K3also uncouples. At this moment, the torque of the spiral spring 310becomes free and acts via the coupling shaft 230 and the coupling sleeve120 on the threaded rod 190. Hereby, these parts are set in ananticlockwise rotation. Through its thread engagement with the threadedrod 190, the thrust sleeve 90 undergoes an axial displacement in thedistal direction. Via the thrust flange 100, the thrust sleeve advancesthe stopper 41 in the carpule 40. In this way, the medicament isdistributed or injected.

During the distribution or injection process, axial forces act on thethrust sleeve 90: The torque of the spiral spring 310 is converted intoa force in the thrust direction, which advances the stopper 41 in thecarpule 40. These forces are absorbed by the ball bearings between thecoupling sleeve 12 and the guide sleeve 110 and the bearing holder 130,in a low-friction manner, so that counter forces (i.e., frictionalcounter forces), which could reduce the driving torque, are minimized.

In the distribution, the display drum 70 is entrained by the rotation ofthe transmission sleeve 210 anticlockwise and is moved in the distaldirection due to its engagement with the stationary mechanism holder150, until it assumes its distal initial position. In this position, itis prevented from rotating further by a radial stop, whereby thedistribution is terminated. After the end of the distribution, thedisplay drum 70 indicates the dose “zero”.

The distribution can be interrupted at any time by the push button 80being released. Thereby, the couplings K3 and K2 couple again, and thecoupling K1 uncouples again. The display drum 70 indicates the remainingresidual dose which is further distributed when the push button ispressed again and thereby the distribution is continued.

The dose limiting ring 220 maintains its axial position during thedistribution, because the transmission sleeve 210 and the couplingsleeve 120, between which the dose limiting ring 220 is situated, rotatesynchronically.

After the end of the distribution, the injection device is ready for thenext injection process. Compared with FIG. 16, however, two componentshave changed their position: On the one hand, the thrust sleeve 90 hastravelled in accordance with the distributed dose in the distaldirection. On the other hand, the dose limiting ring 220 has likewisetravelled by an amount proportional thereto in the proximal direction.Apart from this, the state after the end of the injection corresponds tothe initial state of FIG. 16. With each further injection, the thrustsleeve 90 therefore travels further in the distal direction, whereas thedose limiting ring 220 travels in the proximal direction. This isillustrated in FIG. 19, which illustrates the injection device after afirst dose is administered, which corresponds to half the maximumindividual dose, and then with the dosing sleeve a dose was again set,which in turn corresponds to half the maximum individual dose. Thedisplay drum indicates, as in FIG. 15, half the maximum individual dose,whereas the dose limiting ring 220 assumes a position in thetransmission sleeve 210, which corresponds to the sum of the doses whichhave been set, e.g., twice half the maximum individual dose.

The maximum axial path by which the dose limiting ring 220 can travel inthe proximal direction in the transmission sleeve corresponds to thecontent of a completely filled carpule. As soon as the sum of the dosesset on the dosing sleeve corresponds to the carpule content, the doselimiting ring 220 reaches its proximal final position and abuts with itsradial stop against the axial ring flange 235 of the coupling shaft 230,as is illustrated in FIG. 12A. Thereby, the dosing sleeve 60 isprevented from a further clockwise rotation, and no larger dose can beset than the dose corresponding to the remaining residual amount of themedicament in the carpule. FIG. 20 shows this situation, in which nofurther increasing of the dose is possible, although the display drum issituated in the distal initial position, i.e., the zero position.Correspondingly, the thrust sleeve 90 has reached its maximum, distalfinal position.

To exchange the carpule, the carpule sleeve 30 is detached from themechanism holder 150 against the elastic resistance of the bayonetspring 170, and is unscrewed, guided through the corresponding guideslit 156 in the mechanism holder. Compulsorily, the bayonet sleeve 160is twisted along its own, parallel guide slit 155, and is displaced inthe distal direction. The guide sleeve 110 is drawn in the distaldirection, and the movable parts, which are connected axially therewith,also travel in the distal direction, including the coupling sleeve 120,the threaded rod 190, the arresting sleeve 280, the transmission sleeve210, the coupling shaft 230, the coupling disc 270 and the push button80. The push button 80 is therefore drawn into the dosing sleeve 60 andthus indicates that the injection device is not ready for operation.

Through this axial displacement of the various parts of the mechanism,the couplings K2 and K3 come out of engagement, while K1 is already outof engagement. If a dose had still been set before the carpule change,but had not been administered, the wound spiral spring 310 sets thecoupling shaft 230 and the transmission sleeve 210 connected therewithinto an anticlockwise rotation, until the display drum 70 has reachedits distal final position and prevents a further turning back by itsradial stop on the mechanism holder 150. In this way, the display drum70 is brought back into its distal initial position, the zero position.An automatic resetting of the dose display to zero therefore takesplace.

If, before the carpule change, a residual amount of the medicament wasstill situated in the carpule 40, then the thrust sleeve 90 had not yetmoved out to a maximum before the carpule change, and had therefore notyet reached its distal final position. On removal of the carpule sleeve30, the helical spring 190 presses the guide needle 200, the thrustflange 100 and the thrust sleeve 90 in the distal direction. Thus, thethreaded rod 180 is set in rotation via its screw connection with theinterior of the thrust sleeve 90. The threaded rod 180 entrains thecoupling sleeve 120 and the dose limiting ring 220. With this rotation,the dose limiting ring 220 is displaced into its proximal final positionthrough its thread engagement with the transmission sleeve 210. As soonas the dose limiting ring 220 has reached this initial position, itprevents a further rotation of the coupling sleeve 120 and of thethreaded rod 180, so that no further moving out of the thrust sleeve 90is possible, and the thrust sleeve 90 has reached its distal finalposition, as illustrated in FIG. 1A. In addition, the display drum 70 issituated in the zero position, the dose limiting ring 220 in theproximal final position and the thrust sleeve 90 in its distal finalposition.

A new carpule 40 may be pushed into the carpule sleeve 30, and thecarpule sleeve 30 with the carpule 40 held therein may be guided axiallyin the proximal direction against the housing sleeve 20. In thisposition, the stopper 41 of the carpule presses the thrust flange 100and the thrust sleeve 90 against the force of the helical spring 190 inthe proximal direction. As a result, the threaded rod 180 is set inrotation. The threaded rod entrains the coupling sleeve 120 and the doselimiting ring 220. The dose limiting ring, threadably engaged with thetransmission sleeve 210, is displaced in the distal direction, i.e., inthe direction of its initial position. The degree of displacement inthis direction corresponds to the dose present in the carpule 40. With acompletely filled carpule, the dose limiting ring 220 travels into itsdistal initial position. The carpule sleeve 30 is then pushed into themechanism holder 150, with the radial pins 36 of the carpule sleeve 30engaging again into the guide slits 156 in the mechanism holder 150 (cf.FIGS. 1 and 3). Through the positive guidance of the carpule sleeve 30on insertion into the mechanism holder 150, the bayonet sleeve 160 isforced to follow the movement of the carpule sleeve 30 in thecorresponding guide slits. The bayonet sleeve 160 is thereby broughtback into its proximal final position, in which it is detachably lockedby the bayonet disc 170 (cf. FIGS. 8 to 10). The injection device isthus situated in the initial position of FIG. 16 and, after the screwingof a new needle holder 31, is available for a new sequence ofadministrations.

In FIG. 21, another exemplary embodiment of an injection deviceaccording to the present invention is illustrated as a variant. The modeof operation is substantially the same as in the first embodimentdescribed above. Parts which perform similarly are therefore designatedby the same reference numbers as in the first embodiment, thedifferences of the second embodiment being described below.

In the second embodiment, the stop sleeve 240 is omitted. Rather, itsfunction is taken over by the correspondingly extended housing sleeve20.

The drive arrangement which, in the first embodiment, apart from thespiral spring 310, is formed from the coupling disc 270, coupling shaft230 and transmission sleeve 210, is formed in the second embodiment bydifferent parts, including a connecting shaft 400 (with coupling disc401 formed integrally thereon), a first transmission sleeve 410 closedat the proximal end, and a second transmission sleeve 420 adjoiningdistally thereto. These three parts are, in turn, connected rigidly witheach other.

Whereas in the first embodiment, the display drum served to indicate theset dose and to delimit the maximum individual dose which was able to beset in the dosing direction and to delimit the movement in thedistribution direction, the latter function in the second embodiment istaken over by a second dose limiting ring 430. The latter is guided soas to be locked against relative rotation, but axially displaceable, inthe housing sleeve 20. With an internal thread it runs on acorresponding external thread of the first transmission sleeve 410. Itsaxial movement is limited by two radial stops between a distal initialposition, which corresponds to the zero position, and a proximal finalposition, which corresponds to the maximum dose which is able to be set.In this way, it takes over the stop functions of the display drumaccording to the first embodiment.

The display drum 70 in the second embodiment is guided axiallydisplaceably via a carrier sleeve 440, rigidly connected therewith, andso as to be locked against relative rotation on the second transmissionsleeve 420. Its mode of operation is otherwise identical to the firstembodiment.

Apart from these differences, the structure and mode of operation of theinjection device are substantially the same as in the first embodiment.

The differences between the first and the second embodiment show thatthe functions of an injection device according to the present inventioncan be reached in a variety of ways and the invention is in no wayrestricted to the exemplary embodiments. Various further modificationsare possible, which may be due to manufacturing requirements.

Embodiments of the present invention, including preferred embodiments,have been presented for the purpose of illustration and description.They are not intended to be exhaustive or to limit the invention to theprecise forms and steps disclosed. The embodiments were chosen anddescribed to provide the best illustration of the principles of theinvention and the practical application thereof, and to enable one ofordinary skill in the art to utilize the invention in variousembodiments and with various modifications as are suited to theparticular use contemplated. All such modifications and variations arewithin the scope of the invention as determined by the appended claimswhen interpreted in accordance with the breadth they are fairly,legally, and equitably entitled.

1. An injection pen for the administering of a fluid product, theinjection pen comprising: a housing; a delivery element for deliveringthe product from a reservoir, wherein the delivery element is movablerelative to the housing along a thrust axis, wherein the deliveryelement has a circular cylindrical, outer wall region and wherein thedelivery element comprises an internal thread having a threaded axisrunning along the thrust axis; a thread element comprising an externalthread in engagement with the internal thread of the delivery element,wherein the thread element is configured to be fixed relative to thehousing along the thrust axis and configured to be set into a rotarymovement about the thrust axis to advance the delivery element along thethrust axis; and a guide sleeve with a proximal and a distal end, whichat least partially radially surrounds the delivery element, said guidesleeve, close to its distal end, being coupled with the housing so as tobe locked against relative rotation, and wherein the delivery element,in the region of a proximal end of the delivery element, is in anengagement locked against relative rotation and displaceable within theinterior of the guide sleeve, with the guide sleeve having a lengthalong the thrust axis corresponding at least to a thrust range of thedelivery element, defined by a distance between an initial position anda final position of the delivery element after product delivery.
 2. Theinjection pen according to claim 1 wherein the delivery element has asubstantially smooth outer wall region, the axial length of whichcorresponds to the thrust range.
 3. The injection pen according to claim2 wherein the substantially smooth outer wall region of the deliveryelement is a region of the outer peripheral surface of the deliveryelement that lacks any technically necessary structures.
 4. Theinjection pen according to claim 3 wherein the region of the outerperipheral surface of the delivery element that lacks any technicallynecessary structures, lacks any threads or grooves.
 5. The deviceaccording to claim 2 wherein a region arranged proximally from thesubstantially smooth outer wall region of the delivery element isnormally situated permanently inside the housing and has guidingstructures kept invisible to the user.
 6. The injection pen according toclaim 1 further comprising a dose setting mechanism that selectsdelivery of a selected dose that consumes a portion of the thrust rangeof the delivery element.
 7. The injection pen according to claim 1further comprising a final dose limiting arrangement that at leastpartially encircles the guide sleeve and advances with dose settingtoward a stop that limits the size of the final dose selectable from thereservoir.
 8. The injection pen according to claim 1 wherein thedelivery element has an inter-engagement with the guide sleeve thatconstrains the delivery element to a linear motion without rotationabout the thrust axis notwithstanding rotational forces from theexternal thread of the thread element in engagement with the internalthread of the delivery element.
 9. The injection pen according to claim8 wherein a rotary movement of the thread element is converted into anadvancing movement of the drive element.
 10. An injection pen for theadministering of a fluid product from a reservoir having a dose limitingarrangement which allows the user to set as a maximum the remainingavailable residual dose of the reservoir comprising; a transmissionsleeve which sleeve at least partially surrounds a coupling sleeve thatrotates around a longitudinal axis of the pen; said coupling sleevebeing coupled for selective rotation around the longitudinal axis of thepen during dose setting; a dose limiter which is situated between thetransmission sleeve and the coupling sleeve and which is threadedlyengaged with the interior of the transmission sleeve and secured withregard to rotation on the coupling sleeve; such that during dose settingthe dose limiter is axially displaced in the transmission sleeve via itsthreaded engagement with the transmission sleeve, and during dosedelivery, the transmission sleeve, the dose limiter and the couplingsleeve rotate synchronically around the longitudinal axis of the pen andthe dose limiter maintains its axial position relative to the couplingsleeve, whereby a thrust sleeve undergoes an axial displacement withoutrotation to inject a medicament and the maximum axial path by which thedose limiter can travel in the transmission sleeve corresponds to thecontent of a completely filled reservoir and as soon as the sum of thedoses set corresponds to the content of a completely filled reservoir,the dose limiter reaches its final axial position and abuts with aradial stop on the transmission sleeve thereby preventing further dosesetting.
 11. An injection pen according to claim 10 wherein thetransmission sleeve has an internal threading matching an externalthreading of the dose limiter.
 12. An injection pen according to claim10 wherein the coupling sleeve has at least one longitudinal rib forsecuring axial rotation of the dose limiter.
 13. An injection penaccording to claim 12 wherein the dose limiter is a dose limiting ringsurrounding the coupling sleeve and having an external threadingmatching the internal threading of the transmission sleeve andlongitudinal grooves on the inside to match the at least onelongitudinal rib of the coupling sleeve.
 14. An injection pen accordingto claim 10 wherein the coupling sleeve has a plurality of longitudinalribs for securing axial rotation of the dose limiter.